Since products displayed in a supermarket or a convenience store are sold generally from products at a front line on a display shelf, a vacancy is generated at the front on the shelf as time elapses. For this reason, a clerk periodically walks around to appropriately do work such as supplying of products and what is called “taking out to front” to make arrangement on the display shelf.
PTL 1 describes a stock condition management method of notifying a clerk of a stock condition of products when the product runs out on a display shelf. In the management method described in PTL 1, a real-time camera monitors an image of the display shelf of products, and when a product nonexistence marker provided on the display shelf is detected, a product related to the product nonexistence marker is specified to output a message indicating that the stock is being checked.
Further, PTL 2 discloses a product monitoring system in which a camera captures an image of a display state of products on a display shelf, the image is analyzed, and on the basis of time sequence change of the analysis result, a timing of supplying products is notified.